Dohrmann C, Azpiazu N, Frasch M
Max-Planck-Institut für Entwicklungsbiologie, Abteilung III Genetik, Tübingen, Germany.
Genes Dev. 1990 Dec;4(12A):2098-111. doi: 10.1101/gad.4.12a.2098.
Several Drosophila homeo box genes have been shown to control cell fates in specific positions or cell groups of the embryo. Because the mechanisms involved in the pattern formation of complex internal organs, such as the musculature and the nervous system, are still largely unknown, we sought to identify and analyze new homeo box genes specifically expressed in these tissues. Here, the molecular analysis and expression pattern of one such gene, containing both a homeo box and a PRD repeat, is described. This gene, designated S59, is expressed in a small number of segmentally repeated mesodermal cells approximately 2 hr postgastrulation. Gradually, four groups of S59-expressing mesodermal cells appear in each abdominal hemisegment, each one giving rise to a particular somatic muscle after fusion with surrounding myoblasts. Thus, individual precursors for particular muscles, which we call "founder cells," are specified relatively early during mesodermal development. The expression of a particular homeo box gene in these cells suggests that distinct programs of gene expression are active in subsets of mesodermal cells after germ band elongation, resulting in a specification of their developmental fates. In addition to the mesoderm, S59 is expressed in a subset of neuronal cells of the CNS and their precursors and also in cells of a small region of the midgut.
已有研究表明，几种果蝇同源异型盒基因可控制胚胎特定位置或细胞群中的细胞命运。由于诸如肌肉组织和神经系统等复杂内部器官的模式形成机制在很大程度上仍不清楚，我们试图鉴定和分析在这些组织中特异性表达的新同源异型盒基因。在此，描述了其中一个同时包含同源异型盒和PRD重复序列的基因的分子分析和表达模式。这个名为S59的基因，在原肠胚形成后约2小时，在少数呈节段性重复的中胚层细胞中表达。逐渐地，在每个腹部半节段中出现四组表达S59的中胚层细胞，每组细胞在与周围的成肌细胞融合后形成特定的体壁肌肉。因此，特定肌肉的单个前体细胞，即我们所称的“起始细胞”，在中胚层发育过程中相对较早地就被确定了。特定同源异型盒基因在这些细胞中的表达表明，在胚带延伸后，不同的基因表达程序在中胚层细胞亚群中活跃，从而决定了它们的发育命运。除了中胚层，S59还在中枢神经系统的一部分神经元细胞及其前体细胞中表达，也在中肠一小区域的细胞中表达。
